Reproduction (D)

Question 1

How are sperm cells specialised?

Answer 1

1) Acrosome containing digestive enzymes to break the zona pellucida of the egg cell to fertilise the egg
2) Flagellum allows sperm to swim to ovum
3) Mid section packed with mitochondria provide ATP for the tail to swim

Question 2

How are egg cells specialised?

Answer 2

1) Very large space at its centre containing food for the zygote
2) Zona pellucida is a protective jelly layer which hardens to prevent lots of sperm entering the ovum

Question 3

Explain the acrosome reaction?

Answer 3

The sperm follows the chemical trail of the egg through the uterus into the oviduct where the ovum is
Then the acrosome uses its digestive enzymes to break into the zona pellucida of the egg

Question 4

Explain the cortical reaction?

Answer 4

The egg cell releases cortical granules into the empty space between the membrane and zona pellucida
This causes the zona pellucida to rapidly thicken and harden and stop multiple sperm fertilising the egg and only the sperm’s nucleus enters

Question 5

Explain how nuclei fuse in reproduction?

Answer 5

The sperm cell and ovum’s nuclei fuse into each other forming a zygote containing 46 chromosomes
The zygote divides by mitosis to form an embryo